In a production of a semiconductor device, various processing such as a film deposition or etching is performed on a workpiece so as to form a fine pattern on the workpiece. For example, such processing is performed by generating plasma of gas in a processing container and exposing the workpiece to the plasma. In recent years, there is a tendency that the pattern formed on the workpiece becomes finer. According, a more accurate processing technology is required. In order to form a fine pattern, a technology which alternately supplies gases different from each other to form a pattern on the workpiece is known.
For example, Patent Literature 1 discloses that a step of supplying a deposition gas to generate plasma of the deposition gas and a step of supplying an etching gas to generate plasma of the etching gas are alternately repeated to form a deep hole on a workpiece. In order to perform such processing, an apparatus disclosed in Patent Literature 1 includes a gas supply source, a shower head, a first gas supply line, and a second gas supply line. The etching gas supplied from the gas supply source is introduced into a gas diffusion chamber formed inside the shower head through the first gas supply line. The deposition gas supplied from the gas supply source is introduced into the gas diffusion chamber through the second gas supply line. A valve which switches between supplying and stopping supply of the gas with respect to the gas diffusion chamber is provided in each of the first gas supply line and the second gas supply line.
In the apparatus disclosed in Patent Literature 1, the deposition gas is supplied to the second gas supply line in a state where the valve of the second gas supply line is closed immediately before the gas supplied to the shower head is switched from the etching gas to the deposition gas. Accordingly, an internal pressure of the second gas supply line on the upstream side of the valve increases. As a result, a pressure difference between the inside (the inside on the upstream side) of the second gas supply line and the inside of the gas diffusion chamber is generated. In addition, when the gas supplied to the shower head is switched from the etching gas to the deposition gas, the deposition gas rapidly flows into the gas diffusion chamber by opening the valve of the second gas supply line. Moreover, the deposition gas is supplied to the first gas supply line in a state where the valve of the first gas supply line is closed immediately before the gas supplied to the shower head is switched from the deposition gas to the etching gas. Accordingly, an internal pressure of the first gas supply line on the upstream side of the valve increases. In addition, when the gas supplied to the shower head is switched from the deposition gas to the etching gas, the etching gas rapidly flows into the gas diffusion chamber by opening the valve of the first gas supply line. In this way, in the device disclosed in Patent Literature 1, a switching time between the process of generating plasma of the deposition gas and the process of generating plasma of the etching gas is shortened by causing the gas inside the gas supply line to rapidly flow into the diffusion chamber.